How To Get The Ending
In order to get the ending you must collect all effects, after that you will have to interact with the blue bird that takes you to the wings effect. Then you will view an event with a little boy, interact with him and you'll wake up. Go back to the hospital ward where Kamitsuki's mother is, interact with her and you'll be forced to wake up again. Go through the door that leads to the hospital. You will enter a different room with a person who looks like a white-haired Kamitsuki, you need to kill him. This will trigger the ending.
Effects Guide
This is a list of the effects (aka Items) and where to find them.
Sword
Found in Kamitsuki's dream room.
Box
Nexus → Black Door → School
Game Console
Nexus → Rainbow-colored Door → Game Consoles World
Curry
Nexus → Brown Door
X Band-Aid
Nexus → Tears Door
Wings
Nexus → Cages World → Blue Bird World
Black Page
Nexus → Black Door → School → Hell
White Page
Nexus → Tears Door → "Unneeded" World → Experimental Facility
Yellow Page
Nexus → Brown Door → Gears World → Laboratory → Yellow Room
Blue Rubber Band
Nexus → Eyeball Door → Eyes World
Sign
Nexus → Eyeball Door → Raw Land
Brown Page
Nexus → Rainbow-colored Door → Building Block World
Bear
Nexus → Cages World → Forest
Magician
Nexus → Eyeball Door → Eyes World → Pink World
Dracula
Nexus → Black Door → School → Hell → Victimization → Demon King Room → Castle
Poseidon
Nexus → Black Door → School → Sea World
Chocolate
Nexus → Brown Door → Gears World → Sweets World
Hockey Mask
Nexus → Cages World → Desert
Makeup
Nexus → Eyeball Door
Machine
Nexus → Brown Door → Gears World
Sensitive to Cold
Nexus → Tears Door → "Unneeded" World → Experimental Facility → Snow World → Igloo
Demon King
Nexus → Black Door → School → Hell → Victimization → Demon King Room